1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention provides minimally invasive methods and devices for percutaneous transcatheter implantation of expansible prosthetic heart valves within or adjacent a valved anatomic site within the heart.
Natural heart valves, such as aortic valves, mitral valves, pulmonary valves, and tricuspid valves, often become damaged by disease in such a manner that they fail to maintain bodily fluid flow in a single direction. A malfunctioning heart valve may be stenotic (i.e., heart leaflets are closed down) or regurgitant (i.e., heart leaflets are wide open). Maintenance of blood flow in a single direction through the heart valve is important for proper flow, pressure, and perfusion of blood through the body. Hence, a heart valve that does not function properly may noticeably impair the function of the heart.
The etiologies commonly associated with a malfunctioning heart valve may be congenital, acquired, infectious, or degenerative. The most commonly affected heart valves are the aortic and mitral valves. It is believed that rheumatic heart disease, trauma, and bacterial endocarditis may be largely responsible for aortic stenosis and regurgitation. Common causes of mitral valve malfunctioning may be rheumatic diseases, enlargement of a left ventricle, or endocarditis. Pulmonary valve stenosis may be a congenital heart defect. Common causes of tricuspid valve malfunctioning may be rheumatic heart disease or heart defect.
Cardiac valve prostheses are well known in the treatment of heart disease to replace malfunctioning heart valves. Heart valve replacement generally has been accomplished by major open heart surgery. This is a serious operation that requires general anesthesia, full cardiopulmonary bypass with complete cessation of cardiopulmonary activity, an extended hospitalization stay, and several more weeks to months of recuperation time. For some patients, open heart surgery is not an option because of the critical condition of the patient, advanced age, co-existing infection, or other physical limitations.
An alternative treatment regiment to open heart surgery is minimally invasive intravascular delivery and implantation of prosthetic heart valves, typically by way of catheterization. In minimally invasive procedures, a catheter is used to insert a mechanical or bioprosthetic valve in a lumen of a central blood vessel via percutaneous entry through a distal blood vessel. Typically, such percutaneous prosthetic valve devices comprise an expandable stent segment, a stent anchoring segment, and a flow-regulation segment, such as a ball valve or a leaflet. While such minimally invasive prosthetic devices and methods are promising from safety, patient recovery, and cost standpoints, some drawbacks still need to be addressed. For example, some prosthetic heart valve structures which attempt to mimic locally stiffened tissue of natural valves often fatigue or may even fail with continued or prolonged opening and closing of the valve. This may especially be a problem for prosthetic aortic valve replacements due to the associated high blood pressures and flow rates at this anatomic site.
For these reasons, it would be desirable to provide improved devices and methods for replacing or repairing a malfunctioning heart valve. In particular, it would be desirable to provide improved minimally invasive methods and devices for percutaneous transcatheter implantation of expansible prosthetic heart valves within or adjacent a valved anatomic site within the heart. In particular, it would be desirable to provide improved prosthetic heart valve devices that reduce or inhibit fatigue and/or failure of the valve, particularly the flow-regulation mechanism, during continued or prolonged opening and closing of the valve. It would be further desirable to provide improved prosthetic heart valve devices that effectively maintain bodily fluid flow in a single direction and open and close with pressure and/or flow change of blood through the body. At least some of these objectives will be met by the devices and methods of the present invention described hereinafter.
2. Description of the Background Art
Percutaneous aortic valve replacements are described in U.S. Pat. Nos. 6,482,228 and 5,855,601 and U.S. Publication Nos. 2002/0058995 and 2001/0007956. Other artificial heart valves for implantation within a blood vessel are described in U.S. Pat. Nos. 6,454,799; 6,296,662; 5,957,949; 5,413,599; 4,994,077; 4,352,211; and 3,671,979. Percutaneous venous valve replacements are described in U.S. Pat. No. 6,299,637 and U.S. Publication Nos. 2002/0138135 and 2001/0021872.
The full disclosures of each of the above references are incorporated herein by reference.